The cosine of pi/2 (π/2) is 0.
Here's why:
- Unit Circle: Consider the unit circle, a circle with a radius of 1 centered at the origin of a coordinate plane.
- Angle Representation: An angle of π/2 radians (90 degrees) corresponds to the point where the unit circle intersects the positive y-axis.
- Cosine as x-coordinate: The cosine of an angle in the unit circle is represented by the x-coordinate of the point where the terminal side of the angle intersects the circle.
- Point at π/2: At π/2, the point on the unit circle is (0, 1). Therefore, the x-coordinate is 0.
- Conclusion: Thus, cos(π/2) = 0.
